Arginine (L-arginine), as another amino acid widely used in biologics, has seen significantly increased applications in pharmaceutical preparations in recent years, particularly in high-concentration protein preparations for subcutaneous administration. 

As of 2021, among approved protein-based biologics, 11 antibody products contain arginine, with 10 formulated for subcutaneous use and 1 as a lyophilized powder for intravenous injection. The arginine concentration ranges from 0.028 M to 0.24 M. Some approved biologics containing arginine are listed in the table below. 

Table 2 Examples of Approved Biologics Containing Arginine

Arginine comprises an α-carboxyl group (pKa 2.2), an α-amino group (pKa 9.0), and a guanidinium group (pKa 12.5) (Figure 4).

Unlike histidine, arginine exhibits insufficient buffering capacity within the typical pH range for biologics (5-8) due to its high pKa and therefore must be used synergistically with other buffering agents. Beyond pH regulation with other buffers, arginine also functions as a stabilizer, viscosity reducer and solubilizer in biologics. For example, adding arginine to etanercept can significantly reduce its viscosity. 

In antibody drugs, arginine primarily reduces hydrophobic interactions between protein molecules via charge shielding, thereby inhibiting aggregation. In high-concentration antibody preparations (e.g., SPEVIGO), arginine may markedly decrease the solution viscosity and shorten the injection time. 

Although amino acids are indispensable in protein-based biologics, combining them with other excipients—such as sugars, polyols, and surfactants—can further enhance stabilization for biologics. 

With advancing research, amino acids are emerging in gene therapy and cell therapy. In gene therapy, they may participate in vector construction/modification to enhance efficiency and stability. In cell therapy, they optimize culture conditions to promote cell growth, proliferation, and differentiation, unlocking new possibilities for next-generation biologics. Future rational design and combinatorial optimization of amino acids hold promise for resolving stability and delivery challenges in pharmaceutical development. 

AVT's four injectable-grade amino acid excipients have successfully achieved compliance with mainstream pharmacopoeias (including USP, EP, ChP, etc.), surpassing key performance metrics and fully matching top-tier international brands. Being widely supplied to numerous biopharmaceutical enterprises, they have ensured the stability and safety of biologics and facilitated dual regulatory submissions in China and internationally for domestically developed innovative drugs! 

Stabilizers for Biologics: Guaranteed Domestic Supply, Trust AVT!